Include isdsts field in data

[ethanshar]

isdsts field is missing from data
This PR adds it to the relevant data tasks

[linux-foundation-easycla]

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• ✅ login: ethanshar / name: Ethan Sharabi (db2a6b4)

[gilmoreorless]

Thanks for the PR, but I'm a little confused about its purpose.

Moment Timezone doesn't add the isdst field to the data files because the library doesn't use that field for calculations. There are no changes to the calculation code here that would require the data. Could you elaborate about why this is needed?

Also, this PR only adds the field to the unpacked data file, but not the packed file that is actually shipped with the library.